This application claims the benefit of Japanese Application 2001-096250, filed Mar. 29, 2001, and Japanese Application 2002-076785, filed Mar. 19, 2002, the entireties of which are incorporated herein by reference.
The present invention relates to a production method of a composite material composed of a dispersing agent and a matrix and to a composite material produced by the production method.
A composite material is a composition aggregate in which plural raw materials are macroscopically mixed to provide characteristics, which a raw material alone could not realize, by complementarily utilizing mechanical properties that each raw material possesses. Basically, the method of producing a composite material is a technical method by which a material is combined with other material, and there are various combinations depending on matrixes and dispersing agents, intended purposes, or cost and the like.
Among them, metal matrix composites and intermetallic matrix composites are composite materials that are made by using a metal like Al, Ti, Ni, Nb and others, or an intermetallic compound like TiAl, Ti3Al, Al3Ti, NiAl, Ni3Al, Ni2Al3, Al3Ni, Nb3Al, Nb2Al, Al3Nb and others as a matrix and using an inorganic material like ceramics and others as a dispersing agent. Accordingly, metal matrix composites and intermetallic matrix composites are materials intended for use in the aerospace field and the automobile industry by making the best use of their properties of light weight and high strength, and especially metal matrix composites, in recent years, are contemplated to utilize in many fields, including electronics represented by electronic devices, by making the best use of the properties of low thermal expansion and high thermal conduction.
Production methods of intermetallic compound-based composite material include a method in which intermetallic compound powder is produced by mechanical alloying (MA) and the like in advance, and then the powder is hot-pressed (HP) or hot isostatic-pressed (HIP) with fibers and/or particles as dispersing agent under the conditions of high temperature and high pressure. And, production methods of metal-based composite material include solid state fabrication techniques like a method in which materials are hot-pressed (HP) or hot isostatic-pressed (HIP) under the conditions of high temperature and high pressure, and liquid phase methods like a pressurized impregnation method in which a molten metal is impregnated and a squeeze casting method in which high pressure is needed.
As problems in the conventional production methods for producing metal matrix composites and intermetallic matrix composites, in order to produce fine composite materials, not only do fine matrixes need to be formed by loading high temperature and high pressure in production methods of hot-pressing, hot isostatic-pressing and the like but the performance and scale of production equipment are restricted, consequently there are such problems that it is extremely difficult to produce large-sized or complex-shaped composite materials, in addition, it is impossible to perform a near net shaping in consideration of the shape of an end product, and mechanical processing treatment is needed in a later process.
Further, as a pretreatment process in the production of an intermetallic compound-based composite material, a process is needed to synthesize intermetallic compound powder by mechanical alloying and the like in advance, accordingly there is such a problem that the production process has multiple stages and is complicated. As a result, as described above, the conventional method of producing metal matrix composites and intermetallic matrix composites is an extremely high cost production method because not only does the method need a multistage process but it is carried out under high temperature and high pressure.
In order to solve these problems, Japanese Patent Publication No. 2609376 and Japanese Patent Application Laid-Open No. 9-227969 disclose production methods of composite materials in which methods using a preform composed of a metal oxide and others that can be reduced with Al and the like, the preform is made to react with liquid Al and the like in the surface layer to synthesize aluminide intermetallic compounds and oxides (especially Al2O3) in-situ synthesis.
However, according to the production methods disclosed in Japanese Patent Publication No. 2609376 and Japanese Patent Application Laid-Open No. 9-227969, because the kinds of dispersing agents to be dispersed in obtained composite materials are limited, intended material designs are limited to some specific combinations and it becomes difficult to change the properties of composite materials. Further, the methods have such a problem that if the ratio of materials to be used is not strictly controlled, metal oxides and others or Al and others may remain. Moreover, since a large quantity of reaction heat is generated in a moment, there may be some cases where reaction control is difficult.
On the other hand, among composite materials, porous composite materials having a lot of pores (hereinafter described as xe2x80x9cporous composite materialsxe2x80x9d) exhibits various kinds of effect due to as well as being light compared to composite materials having fine microstructures (hereinafter described as xe2x80x9cfine composite materialsxe2x80x9d). In addition, in the case that pores are introduced into the matrix, generally, mechanical properties such as strength, Yong""s modulus and the like decrease though the material becomes lighter as its porosity increases.
Further, up to now some trials have been performed to make obtained porous composite materials light by making hollow particles compound with a metal of Al or the like, and there has been mainly employed as a production process a pressurized impregnation method in which operations under pressure are required when a metal of Al or the like is impregnated into gaps among hollow particles. According to the pressurized impregnation method, however, there are such problems that crushing, breaking or the like are easily caused in hollow particles when a metal of Al or the like is impregnated. That is, hollow particles are broken due to static pressure of a molten metal in the case that a higher pressure is applied to the molten metal to impregnate it into the gaps, and the molten metal occupies the inner portions of the broken hollow particles. This results in failure to lightening the product. On the other hand, however, the gaps among the hollow particles will not be fulfilled sufficiently with the molten metal, in the case that a pressure for impregnating the molten metal into the gaps is reduced so as not to break the hollow particles. This results in the formation of internal defects, such as cavities. Consequently, there are some cases that expected properties, e.g., light weight are not given to obtained composite materials or that the improvements in the specific strength, specific elasticity, and the like were not achieved.
The present invention has been done in view of these problems associated with conventional arts and aims at providing a production method and composite materials produced by the production method, which production method reduces and simplifies the production processes and at the same time, produces a metal-based composite material, an intermetallic compound-based composite material, and a composite material in a state in which a metal and an intermetallic compound are mixed is used as a matrix, which composite materials are also applicable to large-sized and complex-shaped end products.
That is, according to the present invention, there is provided a production method of a composite material composed of a dispersing agent and a matrix, which comprises: forming a metal-coated layer on the surface of said dispersing agent to prepare a metal-coated dispersing agent, filling said metal-coated dispersing agent in a jig prepared in a fixed shape, and then causing the reaction of said metal-coated layer with molten Al by impregnating said filled metal-coated dispersing agent with said molten Al to form said matrix.
In the present invention, it is preferable that a metal-coated layer that is composed of Ni and has the thickness of below 1% with respect to the average particle size of the dispersing agent is formed using below 4 mass % of Ni with respect to the total amount of molten Al and Ni, and whole the matrix is made of Al. And it is also preferable that a metal-coated layer that is composed of Ni and has the thickness of 1% or more to below 8% with respect to the average particle size of the dispersing agent is formed using 4 mass % or more to below 42 mass % of Ni with respect to the total amount of molten Al and Ni, and whole the matrix is made of a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that a metal-coated layer that is composed of Ni and has the thickness of 8% or more to 24% or less with respect to the average particle size of the dispersing agent is formed using 42 mass % or more to 87.8 mass % or less of Ni with respect to the total amount of molten Al and Ni, and whole the matrix is made of an aluminide intermetallic compound.
On the other hand, in the present invention, it is preferable that a metal-coated layer that is composed of Ti and has the thickness of below 1% with respect to the average particle size of the dispersing agent is formed using below 2 mass % of Ti with respect to the total amount of molten Al and Ti, and whole the matrix is made of Al. And it is also preferable that a metal-coated layer that is composed of Ti and has the thickness of 1% or more to below 12% with respect to the average particle size of the dispersing agent is formed using 2 mass % or more to below 36.5 mass % of Ti with respect to the total amount of molten Al and Ti, and whole the matrix is made of a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that a metal-coated layer that is composed of Ti and has the thickness of 12% or more to 25% or less with respect to the average particle size of the dispersing agent is formed using 36.5 mass % or more to 86 mass % or less of Ti with respect to the total amount of molten Al and Ti, and whole the matrix is made of an aluminide intermetallic compound.
Further, in the present invention, it is preferable that a metal-coated layer that is composed of Nb and has the thickness of below 1% with respect to the average particle size of the dispersing agent is formed using below 4 mass % of Nb with respect to the total amount of molten Al and Nb, and whole the matrix is made of Al. And it is also preferable that a metal-coated layer that is composed of Nb and has the thickness of 1% or more to below 12% with respect to the average particle size of the dispersing agent is formed using 4 mass % or more to below 53 mass % of Nb with respect to the total amount of molten Al and Nb, and whole the matrix is made of a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that a metal-coated layer that is composed of Nb and has the thickness of 12% or more to 25% or less with respect to the average particle size of the dispersing agent is formed using 53 mass % or more to 92.4 mass % or less of Nb with respect to the total amount of molten Al and Nb, and whole the matrix is made of an aluminide intermetallic compound.
In the present invention, it is preferable to form the metal-coated film by any method of electroless plating, CVD (chemical vapor deposition), ion plating as PVD (physical vapor deposition), sputtering, or vacuum evaporation.
On the other hand, according to the present invention, there is provided a production method of a composite material that is composed of a dispersing agent and a matrix, which comprises: forming a metal oxide-coated layer on a surface of said dispersing agent to prepare a metal oxide-coated dispersing agent, filling said metal oxide-coated dispersing agent in a jig prepared in a fixed shape, and then causing the reaction of said metal oxide-coated layer with molten Al by impregnating said filled metal oxide-coated dispersing agent with said molten Al to form said matrix.
In the present invention, it is preferable to use as a dispersing agent any one of inorganic materials of fibers, particles, whiskers, hollow particles, porous bodies with open pores, or porous bodies with closed pores, and further it is preferable to use hollow particles of 0.1 to 30 xcexcm in shell thickness. Moreover, it is preferable to use any inorganic material of Al2O3, AlN, SiC, or Si3N4.
In the present invention, it is preferable to make the volume percentage of a dispersing agent in a composite material to be 20 to 80%. On the other hand, after a metal-coated dispersing agent has been prepared, prior to filling the metal-coated dispersing agent into a jig, it is preferable to mix metal powder with the metal-coated dispersing agent. And it is preferable to use metal powder having particle size at the rate of 0.05 to 80% with respect to the average particle size of the dispersing agent.
On the other hand, according to the present invention, there is provided a composite material comprising a dispersing agent and a matrix, wherein a metal-coated dispersing agent is prepared by forming a metal-coated layer on the surface of said dispersing agent, said metal-coated dispersing agent is filled in a jig prepared in a fixed shape, and the reaction of said metal-coated layer with molten Al is caused by impregnating said filled metal-coated dispersing agent with said molten Al to form said matrix.
In the present invention, it is preferable that the metal-coated layer is Ni, the amount of Ni used is below 4 mass % with respect to the total amount of molten Al and Ni, the thickness of the metal-coated layer is below 1% with respect to the average particle size of the dispersing agent, and whole the matrix is Al. And it is also preferable that the amount of Ni used is 4 mass % or more to below 42 mass % with respect to the total amount of molten Al and Ni, the thickness of the metal-coated layer is 1% or more to below 8% with respect to the average particle size of the dispersing agent, and whole the matrix is a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that the amount of Ni used is 42 mass % or more to 87.8 mass % or less with respect to the total amount of molten Al and Ni, the thickness of the metal-coated layer is 8% or more to 26% or less with respect to the average particle size of the dispersing agent, and whole the matrix is an aluminide intermetallic compound.
On the other hand, in the present invention, it is preferable that the metal-coated layer is Ti, the amount of Ti used is below 2 mass % with respect to the total amount of molten Al and Ti, the thickness of the metal-coated layer is below 1% with respect to the average particle size of the dispersing agent, and whole the matrix is Al. And it is also preferable that the amount of Ti used is 2 mass % or more to below 36.5 mass % with respect to the total amount of molten Al and Ti, the thickness of the metal-coated layer is 1% or more to below 12% with respect to the average particle size of the dispersing agent, and whole the matrix is a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that the amount of Ti used is 36.5 mass % or more to 86 mass % or less with respect to the total amount of molten Al and Ti, the thickness of the metal-coated layer is to 12% or more to 25% or less with respect to the average particle size of the dispersing agent, and whole the matrix is an aluminide intermetallic compound.
Further, in the present invention, it is preferable that the metal-coated layer is Nb, the amount of Nb used is below 4 mass % with respect to the total amount of molten Al and Nb, the thickness of the metal-coated layer is below 1% with respect to the average particle size of the dispersing agent, and whole the matrix is Al. And it is also preferable that the amount of Nb used is 4 mass % or more to below 53 mass % with respect to the total amount of molten Al and Nb, the thickness of the metal-coated layer is 1% or more to below 12% with respect to the average particle size of the dispersing agent, and whole the matrix is a mixture of Al and an aluminide intermetallic compound. Similarly, it is also preferable that the amount of Nb used is 53 mass % or more to 92.4 mass % or less with respect to the total amount of molten Al and Nb, the thickness of the metal-coated layer is 12% or more to 25% or less with respect to the average particle size of the dispersing agent, and whole the matrix is an aluminide intermetallic compound.
On the other hand, according to the present invention, there is provided a composite material comprising a dispersing agent and a matrix, wherein a metal oxide-coated dispersing agent is prepared by forming a metal oxide-coated layer on the surface of said dispersing agent, said metal oxide-coated dispersing agent is filled in a jig prepared in a fixed shape, and the reaction of said metal oxide-coated layer with molten Al is caused by impregnating said filled metal oxide-coated dispersing agent with said molten Al to form said matrix.
In the present invention, it is preferable that a dispersing agent is any one of inorganic materials of fibers, particles, whiskers, hollow particles, porous bodies with open pores, or porous bodies with closed pores, and further it is preferable that the shell thickness of hollow particles is 0.1 to 30 xcexcm. Moreover, it is preferable that the above described inorganic material is any of Al2O3, AlN, SiC, or Si3N4.
In the present invention, it is preferable that the volume percentage of a dispersing agent in a composite material is 20 to 80%. On the other hand, after a metal-coated dispersing agent has been prepared, prior to filling the metal-coated dispersing agent into a jig, it is preferable that metal powder is mixed with the above described metal-coated dispersing agent. And it is preferable that the average particle size of the above described metal powder is at the rate of 0.05 to 80% with respect to the average particle size of the dispersing agent.